Hi,

I'm wondering if anyone here has purchased an aftermarket speedometer from Ebay, usually sold through Hong Kong and Chinese dealers.  These instruments appear like this:



I need to know whether the signals expected by these devices are active low or active high.  For example, many models have gear indicators -- do these gear indicators light up when pulled low to ground or raised high to +12V?  Same goes for turn signal indicators and high beam indicators.

Thanks for any info.

The bottom one is the one that I have for my chookie so after Charlie and me have finished messing about with it and the bits we should be able to tell you.

PM sent Rob with the info that came with the item

Well, well. I just found this connection table on one of the Ebay seller's description page for that particular speedometer, Rick.




This indicates to me that the signals need to go low (grounded) for the majority of the indicators to function.  You and Charlie will have to see if your 4028 based circuit will function, since I think that chip pulls its outputs high.

This indicates to me that the signals need to go low (grounded) for the majority of the indicators to function.  You and Charlie (no not me just Charlie I lost connectivity with this stuff years ago) will have to see if your 4028 based circuit will function, since I think that chip pulls its outputs high.

I need an expert interpreter for Chinglish.  I found instructions for the first pictured tachometer (in the first post).  The bloody meager instructions consist of a badly drawn diagram showing the connector pin mapping.  This they call the "wiring diagram".

The pins are labelled in typical Chinglish ... totally indecipherable.



I'm trying to interpret the pins labelled "Negative" "Power" and "Memory".  I THINK they mean "Ground" "Switched +12V" and "continuous +12V" respectively.  Do others agree with this interpretation?

The reason I ask is that when I apply power to "Power" and "Negative", nothing happens on the meter.  I think I also need constant 12V but don't want to blow up the instrument in case I'm making a mistake interpreting the wiring diagram (it's not mine).

Rob - if it's any help the wiring colours seem to be following Honda specifications. If so,

green is earth
red is unswitched +12v
black is switched +12v
orange is left indicator
light-blue is right indicator
blue is high beam
brown is pilot light (backlighting?)

The rest of them look reasonably self-explanatory?

hi rob ...you will probably find the unswitched + runs the instruments electronics ....the switched + turns on the display
hope that helps

Thanks Dai and Charlie, it works once I hook up both red and black to +12V, green to ground.

Robmack, I am interested to see how you connect all the cables, if you don't mind to show the pictures. Thanks.

I hate to chuck this spanner in the works but I had a Koso instrument (a word I'd use lightly) identical to the bottom image at the top of the thread and the tacho just wouldn't work properly on my K. I tried every way possible to connect it up as per instructions, fitted various filters and the manufactures own device guaranteed to get the thing working to no avail.
I ended up sending it back for a refund. Buy cheap, buy twice rings in my ears again.

Good luck anyway.

sj2000 wrote:Robmack, I am interested to see how you connect all the cables, if you don't mind to show the pictures. Thanks.

I didn't buy or hookup this speedometer to my motorcycle.  I borrowed a gauge similar to the first one pictured at the top if this thread in order to design and test a gear indicator board.  Once I finished the board, I returned the speedometer to its owner.

I documented my K75 build on my blog page if you care to read.